Centralized alarm systems which include a central monitoring station and a plurality of remote subscriber stations are well known. In such systems, the subscriber stations are provided with one or more selected sensors and, either at predetermined times, or upon sensing specified conditions, transmit messages over a communications link to the central monitoring station. The central monitoring station analyzes messages received from the respective subscriber stations and typically provides an output for use by an operator at the central monitoring station. In the present context, a central monitoring station includes any facility such as a hospital, a fire station, a phone answering facility, or a burgular alarm central station monitoring service, in which a centralized monitoring function is performed in response to inputs provided by a number of remote devices operative to sense selected conditions.
In alarm systems such as personal alarm systems, fire alarm systems, burgular alarm systems and the like, reliability of the system is of paramount importance. Subscribers must be assured that, in the event of an alarm condition, the subscriber station will function as intended, for the failure of a system to operate in its intended manner, in certain circumstances, could result in loss of life, personal injury, or significant property damage. It will further be appreciated that the testing of the subscriber stations, which by necessity are diversely located, poses a significant problem. The cost of having service personnel periodically verify the operation of each subscriber station by visiting the sight of the subscriber station to perform hands-on tests is economically prohibitive. Other conventional test methods can sometimes involve up to five telephone communications between the central monitoring station and each subscriber. In one commercial personal alarm system offered by the assignee of the present invention the verification of subscriber system operative involves the following procedure. An operator at the central monitoring station telephones the subscriber and indicates that it is desired to test the subscriber's station. The operator and the subscriber terminate this telephone call and thereafter the subscriber activates an alarm condition at the subscriber station. In response to such activation, the subscriber station automatically dials the central monitoring station and transmits a predetermined message. After receipt of this message at the central monitoring station and termination of this call, the central monitoring station operator once again calls the subscriber to advise of the test result and to request that the subscriber initiate a reset call. After termination of this telephone communication, upon activation by the subscriber, the subscriber station once again initiates an automatic dialing sequence and transmits a second message to the central monitoring station. Following this transmission, the central monitoring station operator may again call the subscriber, advise that the second message has been received, and that the system is operational.
While not all test protocols will necessarily follow this procedure, it is clear that monthly testing of subscriber stations may involve substantial numbers of telephone communications between the central monitoring station and each subscriber station. These calls, particularly in a large alarm system, require a significant investment in time and further burden the processing capabilities at the central monitoring station in view of the need for the central station to process both the alarm message and the second message transmitted by each subscriber station.